From d63b3e7959e79f98d60760a739f7876dc5adc838 Mon Sep 17 00:00:00 2001 From: Richard Levitte Date: Fri, 12 May 2023 10:00:13 +0200 Subject: [PATCH] Restrict the size of OBJECT IDENTIFIERs that OBJ_obj2txt will translate OBJ_obj2txt() would translate any size OBJECT IDENTIFIER to canonical numeric text form. For gigantic sub-identifiers, this would take a very long time, the time complexity being O(n^2) where n is the size of that sub-identifier. To mitigate this, a restriction on the size that OBJ_obj2txt() will translate to canonical numeric text form is added, based on RFC 2578 (STD 58), which says this: > 3.5. OBJECT IDENTIFIER values > > An OBJECT IDENTIFIER value is an ordered list of non-negative numbers. > For the SMIv2, each number in the list is referred to as a sub-identifier, > there are at most 128 sub-identifiers in a value, and each sub-identifier > has a maximum value of 2^32-1 (4294967295 decimal). Fixes otc/security#96 Fixes CVE-2023-2650 Reviewed-by: Matt Caswell Reviewed-by: Tomas Mraz --- CHANGES.md | 27 +++++++++++++++++++++++++++ NEWS.md | 4 ++++ crypto/objects/obj_dat.c | 19 +++++++++++++++++++ 3 files changed, 50 insertions(+) diff --git a/CHANGES.md b/CHANGES.md index cfe2fafa6e..1d497e81ba 100644 --- a/CHANGES.md +++ b/CHANGES.md @@ -284,6 +284,32 @@ OpenSSL 3.1 ### Changes between 3.1.0 and 3.1.1 [xx XXX xxxx] + * Mitigate for the time it takes for `OBJ_obj2txt` to translate gigantic + OBJECT IDENTIFIER sub-identifiers to canonical numeric text form. + + OBJ_obj2txt() would translate any size OBJECT IDENTIFIER to canonical + numeric text form. For gigantic sub-identifiers, this would take a very + long time, the time complexity being O(n^2) where n is the size of that + sub-identifier. ([CVE-2023-2650]) + + To mitigitate this, `OBJ_obj2txt()` will only translate an OBJECT + IDENTIFIER to canonical numeric text form if the size of that OBJECT + IDENTIFIER is 586 bytes or less, and fail otherwise. + + The basis for this restriction is RFC 2578 (STD 58), section 3.5. OBJECT + IDENTIFIER values, which stipulates that OBJECT IDENTIFIERS may have at + most 128 sub-identifiers, and that the maximum value that each sub- + identifier may have is 2^32-1 (4294967295 decimal). + + For each byte of every sub-identifier, only the 7 lower bits are part of + the value, so the maximum amount of bytes that an OBJECT IDENTIFIER with + these restrictions may occupy is 32 * 128 / 7, which is approximately 586 + bytes. + + Ref: https://datatracker.ietf.org/doc/html/rfc2578#section-3.5 + + *Richard Levitte* + * Multiple algorithm implementation fixes for ARM BE platforms. *Liu-ErMeng* @@ -19976,6 +20002,7 @@ ndif +[CVE-2023-2650]: https://www.openssl.org/news/vulnerabilities.html#CVE-2023-2650 [CVE-2023-1255]: https://www.openssl.org/news/vulnerabilities.html#CVE-2023-1255 [CVE-2023-0466]: https://www.openssl.org/news/vulnerabilities.html#CVE-2023-0466 [CVE-2023-0465]: https://www.openssl.org/news/vulnerabilities.html#CVE-2023-0465 diff --git a/NEWS.md b/NEWS.md index 5c52f617e3..0833981522 100644 --- a/NEWS.md +++ b/NEWS.md @@ -38,6 +38,8 @@ OpenSSL 3.1 ### Major changes between OpenSSL 3.1.0 and OpenSSL 3.1.1 [under development] + * Mitigate for very slow `OBJ_obj2txt()` performance with gigantic OBJECT + IDENTIFIER sub-identities. ([CVE-2023-2650]) * Fixed buffer overread in AES-XTS decryption on ARM 64 bit platforms ([CVE-2023-1255]) * Fixed documentation of X509_VERIFY_PARAM_add0_policy() ([CVE-2023-0466]) @@ -1468,6 +1470,8 @@ OpenSSL 0.9.x * Support for various new platforms + +[CVE-2023-2650]: https://www.openssl.org/news/vulnerabilities.html#CVE-2023-2650 [CVE-2023-1255]: https://www.openssl.org/news/vulnerabilities.html#CVE-2023-1255 [CVE-2023-0466]: https://www.openssl.org/news/vulnerabilities.html#CVE-2023-0466 [CVE-2023-0465]: https://www.openssl.org/news/vulnerabilities.html#CVE-2023-0465 diff --git a/crypto/objects/obj_dat.c b/crypto/objects/obj_dat.c index 0ef8330772..116080438b 100644 --- a/crypto/objects/obj_dat.c +++ b/crypto/objects/obj_dat.c @@ -464,6 +464,25 @@ int OBJ_obj2txt(char *buf, int buf_len, const ASN1_OBJECT *a, int no_name) first = 1; bl = NULL; + /* + * RFC 2578 (STD 58) says this about OBJECT IDENTIFIERs: + * + * > 3.5. OBJECT IDENTIFIER values + * > + * > An OBJECT IDENTIFIER value is an ordered list of non-negative + * > numbers. For the SMIv2, each number in the list is referred to as a + * > sub-identifier, there are at most 128 sub-identifiers in a value, + * > and each sub-identifier has a maximum value of 2^32-1 (4294967295 + * > decimal). + * + * So a legitimate OID according to this RFC is at most (32 * 128 / 7), + * i.e. 586 bytes long. + * + * Ref: https://datatracker.ietf.org/doc/html/rfc2578#section-3.5 + */ + if (len > 586) + goto err; + while (len > 0) { l = 0; use_bn = 0;